Počet nalezených dokumentů: 378
Publikováno od do

Porosity of different rocks in relation to capturing/moving of gases and liquids
Řimnáčová, Daniela; Vöröš, Dominik; Natherová, Vendula; Přikryl, R.; Lokajíček, Tomáš
2022 - anglický
Variability in the porosity of natural rocks and waste have been investigated in relation to the influence on the\npermeability of gases and water. The samples were of sedimentary or igneous rocks, carbon-rich rocks, and solid\nporous waste material after thermal conversion. Using mercury intrusion porosimetry, porosity values and pore\nsize distribution varied with the origin of materials. These results have been compared and a connection between\nthe origin and porosity of material was observed. Total porosity values of selected samples ranged from ca. 0.2%\nfor granite to 55% for waste porous material. Lower porosity values demonstrate the connectivity between\nmesopores or micropores and are related to the capturing of greenhouse gases, while higher porosity is caused\npredominantly by the presence of macropores and coarse pores, which serve as pathways for permeability of\ngases and liquids. Klíčová slova: gas adsorption; porosity; rocks; waste materials Dokument je dostupný na externích webových stránkách.
Porosity of different rocks in relation to capturing/moving of gases and liquids

Variability in the porosity of natural rocks and waste have been investigated in relation to the influence on the\npermeability of gases and water. The samples were of sedimentary or igneous rocks, ...

Řimnáčová, Daniela; Vöröš, Dominik; Natherová, Vendula; Přikryl, R.; Lokajíček, Tomáš
Ústav struktury a mechaniky hornin, 2022

Geopolymers: The influence of alkaline activator cations on efflorescence
Novotná, Martina; Polonská, A.; Šídlová, M.; Perná, Ivana
2021 - anglický
This paper describes the effect of the type of cations in the alkaline activator on geopolymer properties and especially on the formation of efflorescence. The susceptibility to the formation of efflorescence is discussed according to the standard ČSN 72 1565-13. Cations in alkaline activators influence the mineralogical type of efflorescence: Li+ and Na+ cations form carbonates (Li2CO3 and Na2CO3, respectively), whereas K+ cations form sulphate (K2SO4). The mechanical properties, workability and pore structure of the geopolymer composites have been determined. Alkaline activators with sodium and potassium ions reach higher mechanical strength than those containing lithium cations. For lithium alkaline activators, there was a noticeable difference in the properties between the SiO2/Li2O ratios 1.8 and 2.6. Based on the properties of the mentioned geopolymer composites with various alkaline cations, it is possible to use lithium alkaline activators in geopolymer technology. Klíčová slova: geopolymer; efflorescence; alkaline activator cations; properties Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Geopolymers: The influence of alkaline activator cations on efflorescence

This paper describes the effect of the type of cations in the alkaline activator on geopolymer properties and especially on the formation of efflorescence. The susceptibility to the formation of ...

Novotná, Martina; Polonská, A.; Šídlová, M.; Perná, Ivana
Ústav struktury a mechaniky hornin, 2021

Three-dimensionally ordered micromesoporous carbon as adsorbent for CO2 capture
Vorokhta, Maryna; Řimnáčová, Daniela; Pilař, Radim
2019 - anglický
In this work, ordered three-dimensionally micromesoporous carbon composed of large spherical mesopores 13 nm in diameter and small micropores with a mean micropore width of 1.46 nm, connecting the main spheres, was synthesized and investigated for CO2 capture ability at temperatures of 25°C, 35°C and 50°C, and at pressures up to 6.5 MPa. Because of the big pore volume occupying 3.62 cm3/g, composed of mesopores and micropores, the carbon sample showed very high adsorption capacity at high pressures. The highest CO2 adsorption capacity of 24.03 mmol/g was obtained at 25°C and at 5.5 MPa. As the temperature increased, the CO2 adsorption capacity decreased to 13.34 mmol/g at 50°C and at 6.5 MPa. The Freundlich fittings of the measured adsorption isotherms at pressures up to 2 MPa showed very high correlation coefficients. The estimated isosteric heats of adsorption in the range of 5.62-6.90 kJ/mol indicated a physical adsorption process, and suggested a stronger interaction between CO2 molecules than between CO2 molecules and the surface of the carbon sample. Klíčová slova: 3DOmm carbon; CO2 adsorption; Freundlich fit; Isosteric heat Dokument je dostupný na externích webových stránkách.
Three-dimensionally ordered micromesoporous carbon as adsorbent for CO2 capture

In this work, ordered three-dimensionally micromesoporous carbon composed of large spherical mesopores 13 nm in diameter and small micropores with a mean micropore width of 1.46 nm, connecting the ...

Vorokhta, Maryna; Řimnáčová, Daniela; Pilař, Radim
Ústav struktury a mechaniky hornin, 2019

Degradation of mechanical properties of magnesium alloy
Sedláček, R.; Suchý, Tomáš; Padovec, Z.
2019 - anglický
In this study, biodegradation behaviour of WE43 magnesium alloy have been studied and compared during exposure to three different media commonly used to simulate the conditions of human body environment. Magnesium alloys emerged as a new class of bioresorbable implant materials. Their applications reduce certain risks associated with conventional permanent implants. Biodegradation behaviour of the WE43 magnesium alloy was observed under Dulbecco Modified Eagle Medium (DMEM, Sigma Aldrich) supplemented with 5 % fetal bovine serum and gentamicin antibiotic as standard. The samples were stored in the medium at 37 degrees C and in a 5 % CO2 atmosphere. The second type of medium was Hank's Salt Balanced Solution (HBSS, Sigma Aldrich), which simulates the inorganic composition of blood plasma. HBSS was tempered at 37 degrees C. The last solution was an acidic solution of HCl + NaCl (pH2) with pH similar to 2 (0.01M HCl and 0.14M NaCl) tempered at 37 degrees C. The acidic type of solution was used to simulate a local acidic environment associated with osteoclast activity during bone remodelling. Changes in the mechanical properties of the samples during exposure to simulated body conditions were observed. Klíčová slova: Bioabsorbable metals; Biodegradation; Magnesium; Implant Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Degradation of mechanical properties of magnesium alloy

In this study, biodegradation behaviour of WE43 magnesium alloy have been studied and compared during exposure to three different media commonly used to simulate the conditions of human body ...

Sedláček, R.; Suchý, Tomáš; Padovec, Z.
Ústav struktury a mechaniky hornin, 2019

Adsorption study of waste materials as potential adsorbents for pollutant removal and storage
Řimnáčová, Daniela; Vorokhta, Maryna; Vöröš, Dominik; Borecká, Lenka; Bičáková, Olga
2019 - anglický
The study shows how changing the experimental conditions during carbonization of a waste material such as sewage sludge influences textural properties and the CO2adsorption capacity of final carbonized productsin their potential use for removaland storage of pollutantssuch as carbon dioxide. The CO2adsorption measurements were done with gravimetric and manometric sorption devices in a wide range of pressures and temperatures. Further, CO2adsorption capacities of other materialssuch as activated carbon prepared from black carbon and a Czech Silurian shalewere compared toadsorption capacities of the studied carbonized sewage sludge. These two compared materials were chosen according to their compositionsand porosity.The porosityof the studied materials was determined from the N2sorption isotherms and measurements of their skeletal density with He.The adsorption capacity depended on the ratio of micropores and mesopores in the carbonized sewage sludge, because CO2fillsmicropores and mesopores at lowand highpressures, respectively, and was decreasing with the temperature increase atconstant pressure.The adsorption capacity of the carbonized sewage sludgewas increased by increase inthe carbonization temperature.The obtained adsorption capacities showed that the carbonization of sewage sludge can lead to preparation of perspective adsorbents for CO2capture and storage. Klíčová slova: CO2 adsorption; high pressure; porous materials Dokument je dostupný na externích webových stránkách.
Adsorption study of waste materials as potential adsorbents for pollutant removal and storage

The study shows how changing the experimental conditions during carbonization of a waste material such as sewage sludge influences textural properties and the CO2adsorption capacity of final ...

Řimnáčová, Daniela; Vorokhta, Maryna; Vöröš, Dominik; Borecká, Lenka; Bičáková, Olga
Ústav struktury a mechaniky hornin, 2019

The processing of stabilized sewage sludge by high-temperature slow pyrolysis and gasification
Bičáková, Olga; Čimová, Nikoleta; Vöröš, Dominik; Náhunková, Jana; Řimnáčová, Daniela
2019 - anglický
One of the most challenging type of waste is sewage sludge, which is a heterogeneous suspension containing organic and inorganic substances and pathogenic organisms. This work focuses on an effective application method for the sewage sludge, which is usually deposited in landfills or co-incinerated in power plants. High temperature pyrolysis and gasification at 700–900 °C were applied to the samples of stabilized sewage sludge. The samples with a constant weight of 100 g were heated in a stationary bed, with the rate of batch heating being monitored. During the heating process, volatile products were released and the composition of the gaseous products developed during the heating was analyzed. Afterwards, the mass balance of the resulting products was evaluated. The elemental and textural analyses of the products were performed. Furthermore, it has been found that the solid residue has a porous texture and properties suitable for the removal and capture of pollutants. \n Klíčová slova: Sewage sludge; pyrolysis; gasification; mass balance Dokument je dostupný na externích webových stránkách.
The processing of stabilized sewage sludge by high-temperature slow pyrolysis and gasification

One of the most challenging type of waste is sewage sludge, which is a heterogeneous suspension containing organic and inorganic substances and pathogenic organisms. This work focuses on an effective ...

Bičáková, Olga; Čimová, Nikoleta; Vöröš, Dominik; Náhunková, Jana; Řimnáčová, Daniela
Ústav struktury a mechaniky hornin, 2019

Mechanical and structural properties of collagen nanofribrous layers under simulated body conditions
Říhová, J.; Suchý, Tomáš; Vištejnová, L.; Horný, L.; Šupová, Monika
2019 - anglický
The theme of this paper is the analysis of mechanical and structural properties of nanofibrous COL under simulated body conditions and in the presence of osteoblasts and dermal fibroblasts. COL were prepared by electrostatic spinning of 8 wt% collagen type I dispersion with 8 wt% (to COL) of PEG in phosphate buffer/ethanol solution (1/1 vol). The stability of COL was enhanced by means of cross-linking with EDC and NHS at a molar ratio of 4:1. COL were exposed in culture medium for 21 days and human SAOS-2 human dermal fibroblasts and osteoblasts were cultured therein for 21 days as well. Klíčová slova: collagen; fibroblasts; osteoblasts; mechanical properties; structural properties; biodegradation Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Mechanical and structural properties of collagen nanofribrous layers under simulated body conditions

The theme of this paper is the analysis of mechanical and structural properties of nanofibrous COL under simulated body conditions and in the presence of osteoblasts and dermal fibroblasts. COL were ...

Říhová, J.; Suchý, Tomáš; Vištejnová, L.; Horný, L.; Šupová, Monika
Ústav struktury a mechaniky hornin, 2019

Valley evolution of the Biala Lądecka drainage network during late Cenozoic, Lower Silesia, Poland
Stemberk, Jakub; Štěpančíková, Petra; Tábořík, Petr; Coubal, Miroslav
2017 - anglický
Biala Lądecka (Biala Kłodzka) river is located in Lower Silesia (Poland) and its valley separates Góry Złote Mts.\n(Rychlebské hory Mts.) on the NE from Góry Bialskie Mts. on the SW. We conducted geomorphic investigations on the Biala\nLądecka river basin, in order to determine if Quarternary tectonic activity at the Bělský fault (or near Marginal Sudetic fault) is\ncontributing to the river’s asymmetry. Our research was focused on analysis of selected landforms, DEM parameters,\nmorphometric indexes and their spatial distribution which could potentially indicate recent tectonic activity in the area. At\nselected places geophysical measures were used to discover proper location and structure of Bělský fault or presence of\nsuggested morpholineaments. Preliminary results suggest a Quaternary tectonic activity for the Bělský fault. Moreover we tried\nto clarify nowadays stress regime in study area based striae measurement on fault planes and precise monitoring of selected\nfaults using TM-71 device. Klíčová slova: Poland - Czech border; NE Europe; stable continental areas; Biala Lądecka river; Bělský fault; morphometric indexes; DEM analysis Dokument je dostupný na externích webových stránkách.
Valley evolution of the Biala Lądecka drainage network during late Cenozoic, Lower Silesia, Poland

Biala Lądecka (Biala Kłodzka) river is located in Lower Silesia (Poland) and its valley separates Góry Złote Mts.\n(Rychlebské hory Mts.) on the NE from Góry Bialskie Mts. on the SW. We conducted ...

Stemberk, Jakub; Štěpančíková, Petra; Tábořík, Petr; Coubal, Miroslav
Ústav struktury a mechaniky hornin, 2017

Late Quaternary activity of slow-slip intraplate Mariánské Lázně fault as revealed by trenching and shallow geophysical survey; Bohemian Massif (Czech Republic, central Europe)
Štěpančíková, Petra; Fischer, T.; Hartvich, Filip; Tábořík, Petr; Rockwell, T.; Stemberk, Jakub; Široký, J.; Sana, Hamid
2017 - anglický
The NNW-SSE trending Mariánské Lázně Fault (MLF) zone is situated in the western part of the Bohemian Massif (Czech\nRepublic, central Europe) where it intersects NE-trending Cenozoic Eger rift. The northern segment of the MLF controls the\nmorphologically pronounced mountain front of Krušné hory Mts. and eastern limit of Cenozoic Cheb basin, which is famous for\nearthquake swarms (max. ML=4.6) and CO2 emanation. We performed 2D and 3D geophysical survey (electric resistivity\ntomography, ground penetration radar) and 3D trenching to look for large surface-rupturing prehistoric earthquake responsible\nfor pronounced moutain range front. Seven excavated and six hand-dug trenches revealed a complex geology and deformation\nat the study site probably as a result of right-lateral transpression during Late Quaternary. Two Holocene earthquakes 1150-590\nBC and 780-1000 AD were inferred from 14C dating of faulted Holocene colluvium with corresponding magnitudes Mw=6.7-7.0.\nThe latter one is the youngest documented surface-rupturing event in central Europe.\n Klíčová slova: paleoseismic trenching; historic earthquake; Cheb basin; Mariánské Lázně fault; Bohemian Massif Dokument je dostupný na externích webových stránkách.
Late Quaternary activity of slow-slip intraplate Mariánské Lázně fault as revealed by trenching and shallow geophysical survey; Bohemian Massif (Czech Republic, central Europe)

The NNW-SSE trending Mariánské Lázně Fault (MLF) zone is situated in the western part of the Bohemian Massif (Czech\nRepublic, central Europe) where it intersects NE-trending Cenozoic Eger rift. The ...

Štěpančíková, Petra; Fischer, T.; Hartvich, Filip; Tábořík, Petr; Rockwell, T.; Stemberk, Jakub; Široký, J.; Sana, Hamid
Ústav struktury a mechaniky hornin, 2017

Field measurement of natural electromagnetic emissions near the active tectonic and mass-movement fractures in caves
Trčka, T.; Macků, R.; Koktavý, P.; Škarvada, P.; Baroň, I.; Stemberk, Josef
2017 - anglický
Laboratory tests on a wide range of solid materials shoved that the electromagnetic emission (EME) signals are generated during the samples mechanical stress. EME anomalies have been observed also under natural conditions in association to fracture processes, tectonic loading, stress redistribution and crack propagation prior to earthquake or in relation to deep-seated gravitational mass movements. This paper describes a first prototype of the Emission data logger, which was specially developed for the continual EME monitoring in field conditions. Our equipment has been installed and tested in Obir Caves (Austria) at an active tectonic fault. The pilot long-term EME measurement results from this location are also presented in this paper. Klíčová slova: Active tectonic fault; Continual monitoring; Emission data logger; Field measurement; Fracture processes; Natural electromagnetic emissions Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Field measurement of natural electromagnetic emissions near the active tectonic and mass-movement fractures in caves

Laboratory tests on a wide range of solid materials shoved that the electromagnetic emission (EME) signals are generated during the samples mechanical stress. EME anomalies have been observed also ...

Trčka, T.; Macků, R.; Koktavý, P.; Škarvada, P.; Baroň, I.; Stemberk, Josef
Ústav struktury a mechaniky hornin, 2017

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